<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>表单</title>
</head>
<body>
<form action="#" method="get" autocomplete="off">
    <select name="city">
        <option>===请选择所在城市===</option>
        <optgroup label="直辖市">
        <option value="bj">北京</option>
        <option value="sh">上海</option>
    </optgroup>
        <optgroup label="省会市">
            <option value="hz">杭州</option>
            <option value="wh">武汉</option>
        </optgroup>
    </select>
    <br/>
    <button type="submit">提交</button>
    <button type="reset">重置</button>
</form>
</body>
</html>